Page 31 - VetCPD Jnl Volume 7, Issue 4

ataxia and rolling) (Capello et al. 2015) (Figure. 5). Often otitis interna and media are combined. In severe cases, otitis interna may extend to the brain, resulting in encephalitis and seizures.
The vestibular system can be approached by assessing the presence of resting and positional nystagmus or strabismus,
the presence of head tilt, and whether
a patient is leaning or falling to one
side. However, the presence and type
of nystagmus does not always aid in distinguishing peripheral from central vestibular disease in the rabbit as positional or resting, horizontal or rotary nystagmus may be seen in both situations. It is often difficult to distinguish between a central or peripheral vestibular problem clinically and further diagnostic tests are required
to identify the exact problem.This is important to define a prognosis and establish an appropriate treatment plan.
VETcpd - Exotics
limb paresis is also common in geriatric rabbits due to degenerative bone and joint disease. Clinical signs are similar to those of traumatic causes.When a spinal cord lesion is suspected, determining which limbs are affected (all four or just the pelvic limbs) can be done by assessing gait, voluntary movement and postural reactions. In other cases, other tests may also need to be performed.
Diagnostic plan
Once the neurological lesion is localised, appropriate diagnostic tests need to be performed in order to achieve a definitive diagnosis.A complete blood count and serum biochemistry panel, urinalysis,
Central (brain) disease the general health status of the patient Animals with brain disease may develop and identification of other systemic
behavioural changes such as aggression, or infectious diseases, which may be
or altered mentation, hypermetria, responsible for the clinical signs observed. hemiparesis with propioceptive deficits or Microbiology, heavy metal blood levels, paralysis, head tilt, circling, rolling and/ cerebro-spinal (CSF) analysis and culture,
or leaning. Circling generally indicates endoscopy, radiology, myelography,
cerebral or thalamic disease (animals may computed tomography (CT) and/or complete wide compulsive circles) or magnetic resonance imaging (MRI) may brainstem disease (tight circles may be seen be further indicated depending on clinical in this case).Abnormal postural reactions and neurological examination findings can be very difficult to interpret as normal (Fisher et al. 2020).
animals may appear to have deficits if
stressed, but ipsilateral postural deficits may
be seen in animals with brainstem disease
and contralateral deficits in those with
thalamic or cerebral disease. Cranial nerve
deficits (such as facial paralysis or vestibular
dysfunction) may be seen in brainstem
disease. Seizures may be seen with cerebral
cortex disease.
Spinal cord lesions
Spinal cord conditions encountered in rabbits may include vertebral fractures or luxations, congenital vertebral abnormalities, vertebral neoplasia,
and discospondylitis (Figure 6).Acute posterior paresis often occurs in rabbits secondary to trauma. Following inappropriate restraint, rabbits can
kick violently with their hind limbs putting tremendous pressure on the lumbosacral spine (Figure 7). Fractures and dislocations occur most commonly at the L6–L7 region. Clinical signs may include paraplegia, loss of deep and superficial pain sensation, and loss of motor control over the bladder and anal sphincter. Chronic, progressive hind
When performing myelographic studies, contrast material may be injected into the subarachnoid space to outline the spinal cord when non-contrast radiography and CSF analysis may have failed to identify the cause of the disease or to obtain more precise information regarding a lesion. However, with less invasive and more advanced diagnostic imaging modalities such as CT and MRI, this is now infrequently performed.
CT is particularly indicated for imaging the skull, middle and inner ear, vertebral column, musculoskeletal system and detection of bone abnormalities (Figures 8 - 9) whereas MRI is a useful technique for identifying soft tissue abnormalities and enable fine detail to be visualised. It is particularly helpful in rabbits with central
and specific serologic (e.g. E.cuniculi and Toxoplasma) and/or Polymerase Chain Reaction (PCR) testing should be considered in most rabbits with neurological disease, based on clinical suspicion.This will allow evaluation of
Subscrib
Only
A CSF sample should be collected caudal
to the lesion (so from the cisterna magna
for rabbits with brain disease and by
cisternal or lumbar subarachnoid puncture
for cases with spinal cord disease).The risks associated with such a procedure should be adequately considered.The sample may be submitted for cytology and microbiology.
Figure 6: This patient was presented for altered gait and difficulty moving. Note the posture of this rabbit at rest. A CT scan confirmed severe diffuse discospondylitis affecting several cervical and lumbo-sacral spinal tracts.
ers
Figure 7: Latero-lateral radiograph of a rabbit presented for acute onset hind limb paralysis following inappropriate handling showing vertebral luxation between T10-11.
Figure 8: Transverse CT multiplanar reconstruction in bone algorithm of the tympanic bullae of a rabbit showing both structures entirely filled with fluid/ soft tissue attenuating substance (yellow arrows). The rabbit had no apparent clinical signs.
Figure 9: Transverse CT multiplanar reconstruction in bone algorithm of the skull of a rabbit showing bilateral expansile middle ear lesions with
bulla osteitis (red arrow heads) and secondary intracranial contact (right > left) in a rabbit presented for head tilt and anorexia.
VETcpd - Vol 7 Issue 4 - Page 29